Street signs are a familiar device to both pedestrians and vehicle drivers. They are part of the class of signs designated as "guide signs" and are found on virtually every street corner to assist the public in street name identification.
Such street signs remain useful only as long as they are properly oriented with respect to the roads or intersections and are in a proper upright configuration to enable immediate recognition by the public. Such immediate observation is necessary in view of the need for motorists to travel at a normal traffic flow rate. Where the driver has to slow down or stop to locate a street sign, a safety risk arises to both pedestrian and vehicle drivers by reason of confusion and traffic congestion typically caused by such action.
To facilitate immediate recognition of street signs as well as other traffic signs, uniform sign shapes have been required by federal legislation. The guide signs have been designated to have a rectangular shape with the long side being horizontal with respect to the ground. A typical street sign in compliance with this configuration is shown in FIG. 1. In this case, two sign blanks 10 and 11 are shown as typically mounted for identification of an intersection of two streets. The size of each blank may range from six inches in height and twenty inches in length, to nine inches in height and fifty inches in length. The size will depend on the speed of traffic and the need for visual awareness on the part of the driver at extended distances.
The configuration illustrated in FIG. 1 is a sign blank combination which is centrally mounted on a post 12 which would probably be located on one or more corners of the intersecting streets. Such posts are typically made of galvanized steel or other sturdy metals capable of supporting the weight of the sign blanks. In accordance with current safety practices, such a street signpost should be of a "breakaway" post which would fail or shear on impact by a vehicle. The safety considerations suggesting the use of breakaway posts are based on the principle that less damage will be done to the vehicle and driver if the post is capable of giving way at impact. Obviously, other safety risks arise by virtue of a post which now may become a flying projectile capable of injuring bystanders.
This hazard is developed by the material composition currently used for street sign blanks. In a report titled "Model Standards for Street Name Signing" prepared by the Uniform Ordinances and Practices Committee of the Southern California Chapter of the American Public Works Association, in 1977, a survey revealed that one-half of such street signs were construed of box-type aluminum or porcelainized steel and the other half were of a blade-type aluminum. It is apparent that the use of the aluminum or steel material as sign blank composition greatly increases the risk of injury when such sign blanks are attached to breakaway posts which may be hurled through the air upon vehicle impact. Despite this risk virtually all street sign blanks continue to be made of these respective metals. This is due in part to the need for stiffness and rigidity in the street sign to ensure its maintenance of proper orientation and stability in the wind.
The street sign blanks such as shown in FIG. 1 are typically mounted by brackets in a crosswise orientation. A post bracket 13 is used to couple the first sign blank 11 to the upright post 12. An interlocking bracket 14 is used to attach the top sign post 10 in crosswise orientation to its supporting sign post 10 in crosswise orientation to its supporting sign blanket 11. These brackets are usually constructed of aluminum and are locked in place by various nut and bolt combinations.
Viewing the current street sign combinations as a whole, it is noted that a high level of rigidity occurs throughout the structure. This rigidity supplies the required stability throughout the post, brackets and sign blank combination. Although such stability is desirable for maintaining proper sign orientation, other problems and disadvantages exist which suggest the need for an improved sign blank material.
For example, one problem with the metal sign blank construction arises because of its rigidity. Specifically, the metal sign blanks will deform on impact and will remain in a bent or misfigured configuration. Once the street sign has been bent out of shape it frequently is difficult for a driver to properly identify the street designated. A preferred structure would incorporate flexibility or elastic character which would restore the sign blank to its proper form.
Unfortunately, this problem of metal deformation due to impact is well-known to vandals. In fact, the deformation of street signs is more commonly caused by deliberate vandalism rather than impact from vehicles or by objects extending from vehicles.
A further problem arises because of the commerical value of aluminum in the present market. The rigid structure of the aluminum sign blank greatly facilitates its theft because it may be broken away from the bracket by a quick twist or jerk. Consequently, many aluminum sign blanks are stolen each year for the sole purpose of resale of the aluminum material.
An additional problem somewhat complimentary to the previous problem noted is the high cost of purchase and replacement for the aluminum and steel sign blank. Quite typically, the purchase of sign blank materials is not a onetime expenditure due to vandalism and other problems, the metal sign blanks must be replaced on occasion. Such replacement costs are quite significant in view of the large number of street sign blanks which are used in any particular city.
A final problem which should be noted is the added risk of injury supplied by a metal sign blank attached to a flying projectile such as a breakaway post. Following impact by a vehicle, the breakaway post shears or splits near ground level and may become a flying object. The attached metal blades at the end of the post, having a high mass, are a hazzard to both property and human life.
The seriousness of these deficiencies is further enlarged by the number of such signs involved. When one considers that every street and intersection must be identified at virtually every intersection, the number of such street signs becomes staggering. Despite the tremendous expense and noted deficiencies of the standard metal street sign configuration, very little improvement has been developed. Specifically, the inventor herein is aware of no attempts to change material composition away from the original metal street sign blanks.
Although no attempts have been made to deal with the problems of high mass and expense of metal street sign blanks, some efforts were made toward changing material composition in regulatory signs such as stop signs and the like. These attempts included the use of fiberglass matt or fabric resin composite materials whose dimensions roughly conformed to the original dimension of the metal sign being replaced. Although the fiberglass material has the advantage of reduced cost and lighter weight, its use was abandoned in view of material failure following attachment to the rigid sign post or other mounting means. As a consequence, the use of fiberglass material as regulatory sign blanks was short-lived.
Other uses of fiberglass as sign material have since emerged. Some signs which are fixed in a rigid frame or which are affixed against a rigid wall have demonstrated the favorable characteristics of weatherability and general utility in an outside environment. Such uses have been limited, however, to methods of attachment which rigidly fix the sign blank such that it is immobilized and unable to vibrate in the wind. In circumstances where an unframed sign blank has been attached to a rigid post or at one of its edges, the material fails at the attachment point and the sign blank proves to be unserviceable.
Other uses have been made of fiberglass composition in connection with signs, as illustrated in U.S. Pat. No. 2,782,544 by Tobin. This disclosure, however, deals only with the manufacture of a sign whose inscription is given a crystalline or sparkling appearance when viewed in the light. This crystalline characteristic is provided by fiberglass which is inlayed in a sign blank with the desired lettering or design format. The inventor is aware of no prior art disclosure as to any specific utility for fiberglass as sign material to be attached to a rigid metal post.
Therefore, in the field of guide signs, as well as other regulatory signs whose method of mounting or attachment consists of bolting the sign blank to a rigid post, the typical means for identification continues to be by a method utilizing metallic sign blanks. As previously noted, the problems inherent in this material include a high cost for initial purchase and subsequent maintenance, with an attendant high risk of theft and vandalism. Furthermore, the risk of such rigid blanks as part of sign material along highways and streets provides added danger to the public when such posts are struck by moving vehicles. What is needed, therefore, is a sign blank material which is inexpensive and durable in the weather, but flexible enough to avoid the need for regular maintenance and light in weight to reduce the risk of injury and damage when struck by moving vehicles.